Diagnosing and Treating Dermatomyositis

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Dermatomyositis is an inflammatory disease that primarily affects the skin and muscles (myopathy) but may also affect other organs of the body. It is often characterized by a skin rash that precedes or appears simultaneously to muscle weakness. Research suggests that dermatomyositis is an autoimmune disorder in which the body attacks its own healthy cells.

Dermatomyositis can occur in people of any age, but typically affects adults between the ages of 40 and 60. It is more prevalent among women than men. The onset of juvenile dermatomyositis begins between 5 and 15.

Symptoms

Dermatomyositis produces a variety of symptoms including:

  • A reddish-purple to dusky-red rash in a symmetrical distribution around the eyes (heliotrope rash)
  • Dark red bumps (Gottron papules) or raised blotches over the knuckles, finger or toe joints, elbows, ankles, or knees
  • Firm yellow or flesh-colored nodules (calcinosis) over the knuckles, finger or toe joints, elbows, ankles, or knees in children with the disease
  • A scaly scalp or diffuse hair loss in some individuals
  • Fatigue or weakness of the muscles when climbing stairs, rising from a sitting position, or lifting arms

Although less common, people with dermatomyositis may also have systemic symptoms such as arthritis, shortness of breath, or difficulty swallowing or speaking. Adults over 60 with dermatomyositis sometimes have a higher risk of developing cancer.

Diagnosis

Skin symptoms appear first with dermatomyositis, so the rash and papules that characterize the disease—and calcinosis nodules in children—suggest a diagnosis. That said, these lesions can sometimes be mistaken for those of lupus erythematosus, psoriasis, or lichen planus.

Blood tests that detect muscle enzymes and markers of inflammation are also used for diagnosis. Some people with the disease test positive with an antinuclear antibody (ANA) blood test. Magnetic resonance imaging (MRI), electromyography (EMG), and muscle biopsy can help assess muscle damage.

Treatment

Treatment for dermatomyositis entails controlling the muscle weakness and skin symptoms. Generally, a corticosteroid, such as prednisone, is administered to decrease muscle inflammation. If the side effects of steroids become severe, immunosuppressant or cytotoxic medications, such as methotrexate (Rheumatrex) or azathioprine (Imuran), may be used. Methotrexate can also help reduce skin symptoms. (Something to remember: People with dermatomyositis are photosensitive and should protect their skin from sun exposure.)

Physical and occupational therapy can help improve muscle function and prevent complications such as contractures, which is a shortening and hardening of muscles or tendons.

Some people with dermatomyositis require treatment for systemic symptoms or complications. In children and adolescents, calcinosis can complicate treatment.

Outlook

Most people with dermatomyositis require long-term treatment. And while some develop cancer or organ failure, which can affect life expectancy, many individuals respond well to treatment and have relief of some or all of their symptoms.

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